JP2008122064A - Frost preventing refrigerating machine and defrosting device for refrigerating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that the quality of a refrigeration function is deteriorated and cost is increased due to frost adhering to an evaporator of a refrigerating machine, causing the deterioration of the efficiency of the refrigerating machine, and the operation of the refrigerating machine must be stopped to carry out defrosting for the removal of the frost. <P>SOLUTION: The evaporator of the refrigerating machine is put in a pressure vessel, cooled to a temperature of 0°C or higher at high temperatures and high pressure, and a low temperature is obtained by expanding it. The leeward side of the pressure vessel can be opened and closed, operation is constantly carried out under atmospheric pressure, the leeward side is closed when the evaporator is frosted, the frost is melted at high temperatures and high pressure, and the cooled air is expanded to obtaine low temperature air. The size and the shape of the evaporator is made coincident with the size and the shape of a portion of the pressure vessel housing the evaporator wherein the air to be cooled is passed through the evaporator. A press-in opening and a discharge opening of the pressure vessel housing the evaporator is made plural in number, or guide plates are provided in the fore-and-aft direction of the evaporator. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigerator that does not frost in an evaporator and a defroster for the refrigerator.

  When the refrigerator is operated, frost forms on the evaporator. The heat conductivity of frost is said to be 1/200 to 1/300 of metal, and heat exchange between the refrigerant and the air to be cooled becomes significantly worse when the thickness of the frost increases. The resistance of the air flowing between the fins of the evaporator is also increased, and the efficiency of the refrigerator is greatly deteriorated.

As for the defrosting method of the evaporator of the refrigerator, there are a natural melting method, a method using hot gas discharged from the compressor, an electric heater method, etc. There is also a method.
There is also an example in which the air to be cooled is cooled with air having a low moisture content using a dehumidifying agent or the like to prevent frost from forming. In this case, two sets of dehumidifying agents are prepared, and the other set is regenerated while one set is dehumidified.

In the frost countermeasure method described above, when the operation of the refrigerator is stopped and defrosting is performed, inconveniences such as an increase in the temperature of the object to be cooled and deterioration in quality occur, and the operating rate of the refrigerator is also deteriorated. Having multiple evaporators eliminates the interruption of the cooling function but increases costs. A method of dehumidifying with a dehumidifier and regenerating the dehumidifier is also costly.
Furthermore, the cooling heat generated by the evaporator of the refrigerator cools the air to be cooled, but a part of it cools and freezes the moisture contained in the air and attaches it to the fins as frost. It is not only useless, but doing more harmful things.

The cold heat of the frost is not used effectively despite the fact that it is a cold heat source similar to the cold heat generated in the evaporator, and the frost is merely heated and melted and discarded.
The present invention creates a refrigerator that can prevent frost from forming on the evaporator, or a refrigerator that can efficiently defrost, and prevents the interruption of the refrigeration function or reduces the adverse effects of the interruption, and the effective use of the cold source of frost. It is intended to be used.

Means for Solving the Invention

A pressure vessel that houses the evaporator of the refrigerator and an air compressor that press-fits air to be cooled into the pressure vessel.
As one method of the refrigerator, the leeward portion of the evaporator can be opened and closed with respect to the pressure vessel that houses the evaporator.
The pressure vessel that houses the evaporator has a size and shape that match the size and shape of the evaporator where the air to be cooled passes through the evaporator. Try to minimize the amount of bypass.
A plurality of pressure inlets and outlets of the pressure vessel are provided, or air guide plates are provided in the front and rear of the evaporator in the pressure vessel so that the air uniformly contacts the evaporator fins.

The invention's effect

  In the present invention, in the system in which the leeward side of the evaporator of the pressure vessel does not open and close, the air to be cooled is pressed into the pressure vessel to increase the temperature and pressure, while frost is generated by the latent heat of evaporation of the refrigerant vaporized by the evaporator. If it is cooled to a temperature where it does not reach and is released outside the pressure vessel, low-temperature air can be obtained without frost formation, and the harmful effects of frost can be eliminated. The useless effect of creating frost can be prevented.

In the system that can open and close the evaporator leeward side of the pressure vessel, the leeward side of the evaporator is normally opened and the operation is performed as usual. .
The air cooled by melting frost is released out of the pressure vessel, and the temperature is lowered. That is, the defrosting efficiency can be improved and the frost can be effectively used.
Currently, a method generally used as an efficient defrosting method is a hot gas method. In this method, refrigerant pipes and fins are heated and frost is melted by the heat. In contrast, in the present invention, high-temperature air directly melts frost, and the refrigerant pipes and fins are hardly heated.

By matching the size and shape of the pressure vessel where the air to be cooled passes through the evaporator, the air to be cooled will not pass outside the evaporator, thus increasing the efficiency of the evaporator. And the required blast energy can be saved.
By providing multiple pressure inlets for high-pressure air to the pressure vessel and multiple outlets from the pressure vessel, and by providing guide plates before and after the evaporator, air can be brought into uniform contact with the fins of the evaporator. Can improve the efficiency of the evaporator.
As described above, the cooling efficiency is improved, and the cooling function is not interrupted, or even if it is interrupted, air that is low in temperature to some extent is supplied, so that stable cooling can be performed.

Especially when storing and transporting foods etc. at 0 ° C or lower without freezing, the allowable temperature fluctuation range is often small, exceeding the upper limit during defrosting, and the goods being stored may be damaged. Since there are many, if this is solved, the merit is great.
In addition, it has great merit for low temperature aging and low temperature drying.
Even if it is a pressure vessel, as can be seen from Table 1 “Relationship table between compression, cooling and temperature after expansion”, a pressure vessel of 0.2 MPa or less, which does not reach the second type pressure vessel, and is less regulated In the pressure vessel, air is compressed and heated to a high temperature, which not only increases the temperature difference from the evaporator or frost, but also increases the air density and heat. The exchange rate increases or the speed of melting frost increases.

注１、本表は、逆ブレイトンサイクルによる計算値であって、圧縮後圧力と冷却後温度は、設定値であり、圧縮後温度と膨張後温度は理論計算値である。したがって、実際の値は、これに効率が加えられた数値になる。また、実際は、圧入されながら冷却されているため計算は複雑なものになる。
注２、膨張後温度欄の等圧とは等圧膨張の場合の計算値、等容とは等容膨張の場合の計算値である。
また、圧縮エネルギ−と温度との関係式Ｉｃ＝Ｃ_ｐ（Ｔ_２−Ｔ_１）から見ても、霜を溶かすのに、多大なエネルギ−を必要とはしない。

Note 1, this table is a calculated value by the reverse Brayton cycle, the pressure after compression and the temperature after cooling are set values, and the temperature after compression and the temperature after expansion are theoretical calculation values. Therefore, the actual value is a value obtained by adding efficiency to this. In fact, the calculation is complicated because it is cooled while being pressed.
Note 2: The constant pressure in the post-expansion temperature column is a calculated value in the case of constant pressure expansion, and the equal volume is a calculated value in the case of constant volume expansion.
The compression energy - even from a relational expression between the temperature _{Ic = C p (T 2 -T} 1), to melt the frost, great energy - do not require.

FIG. 1 is a side view of a pressure vessel and an evaporator (a system having no induction plate) according to the present invention.
The air compressed by the air compressor 1 passes through the compressed air pipe 2 and is pressed into the pressure vessel 4 from one or a plurality of compressed air pressure inlets 3, and reaches the evaporator 5 (main unit) until it becomes hot and does not freeze and freeze. What is visible in the figure is the side plate 6 that fixes the refrigerant pipe in the evaporator and the refrigerant pipe 7 that is U-turned through the side plate that fixes the refrigerant pipe), It is discharged from one or a plurality of air discharge ports 8 and becomes the desired low-temperature air. Condensed water generated when cooled is drained from the drain drain pipe 9.

As the number of compressed air inlets and air outlets increases, the amount of air contacting the evaporator fins becomes more average.
If the number is reduced, the structure will be simple and the equipment cost will be cheap. However, the air flow will not be uniform, so in that case, set the temperature higher after cooling and place fins in a place where the air flow rate is low. However, it is necessary to prevent the temperature after cooling from falling below 273K.
A temperature sensor is provided at the air outlet, and when the temperature of the air rises due to frost on the fins, the pressure and temperature in the pressure vessel are increased, and the effect of frost melting is determined by looking at the effect. Restore the pressure in the pressure vessel. (In this figure, the temperature sensor relationship is omitted.)

In the method of opening and closing the evaporator leeward side (surface with the air discharge port) of the pressure vessel, the leeward side is opened during the cooling operation, and the air sent by the air compressor flows out without increasing the pressure. When the frost arrives and it is necessary to remove the frost, the open leeward side is closed, the pressure container becomes air, and the hot air melts the frost.
FIG. 2 is a cross-sectional view taken along a line XX in FIG. It can be seen that the evaporator occupies almost 100% of the portion through which air passes. Although the fins are tightly attached to the refrigerant piping in the evaporator with a slight gap, they are omitted because the figure becomes complicated.

  The U-turn part of the refrigerant pipe coming out through the side plate of the evaporator has no fins. This part is shielded from air flow, but the part where the refrigerant pipe penetrates the side plate is not airtight and there is a gap between the pressure vessel and the evaporator. It fluctuates according to the pressure in this container. If this plate is used as a part of the pressure vessel with airtightness in the through-hole portion of the refrigerant pipe, the wasteful portion of the pressure vessel is reduced and the economy is improved accordingly.

FIG. 3 is a side view of a pressure vessel and an evaporator according to the present invention, in which induction plates are attached to the front and rear of the evaporator, and further, the expansion energy is recovered by an expansion turbine. It is.
The air press-fitted into the front portion 11 of the pressure vessel from the air compressor (in this case, only the compression turbine) connected to the motor 10 is guided to the induction plate 12 and is supplied to the evaporator of the pressure vessel evaporator section 13. Evenly flows between the fins. An induction plate is also attached to the rear portion of the pressure vessel so that the air flow in the rear portion of the pressure vessel 14 does not disturb this uniform flow.

In the defrosting system, the rear part of the pressure vessel is opened during normal operation, and the air cooled by the evaporator flows out as it is, but when the frost gets on the fins and defrosts, The rear part of the pressure vessel is closed. The air collected by the induction plate at the rear of the pressure vessel enters the dehumidifying device 15 through an air discharge port fixed to the pressure vessel evaporator, is dehumidified, passes through the expansion turbine 16, and is supplied with one of the compression energy. The part is recovered and returned to atmospheric pressure.
Also in this system, a cross-sectional view of the pressure vessel evaporator is as shown in FIG.

FIG. 4 is a diagram of a refrigerator that employs a system in which induction plates are provided at the front and rear of the evaporator shown in FIG. 3 of the present invention, and the rear is opened during the cooling operation. The refrigerant compressed into the high-temperature and high-pressure gas by the refrigerant compressor 17 enters the condenser 18 through the refrigerant pipe, is cooled and liquefied, passes through the expansion valve 19, and is an evaporator in the pressure vessel of the refrigerator compartment 20. Go to, evaporate and cool the air passing through the evaporator, and then return to the refrigerant compressor.
The rear of the pressure vessel is in position A during normal operation. However, if the temperature of the air coming out of the evaporator rises due to frost on the fins of the evaporator, it can be detected and the rear of the pressure vessel can be moved. One or a plurality of sensors (not shown in the figure) installed in an unobstructed position sense this, and are connected and intimately connected to the leeward side of the pressure vessel evaporator.

  The air in the refrigerator compartment is pressed into the pressure vessel by a compression turbine connected to a compressor motor, and the temperature rises to melt frost. Air whose temperature has been lowered while melting frost exits from the pressure vessel, expands, lowers the temperature, and returns to the refrigerator compartment. In a large-scale refrigerator, as shown in the figure, after removing moisture remaining by a dehumidifying film or the like in the dehumidifying device, the expansion turbine can be rotated to recover a part of energy consumed during compression.

The heat pump and the cooling and dehumidifying dryer are almost the same as the refrigerator in the pressure vessel portion, but since the frost forms on the heat pump at the time of heating, the cold heat of the frost cannot be effectively used.
In the cooling and dehumidifying dryer, when the temperature is lowered, the moisture remaining in the air is condensed when the temperature is lowered. Therefore, if the air is removed by a method such as filtration or centrifugation, the drying efficiency is increased (expanded turbine). Is usually dehumidified before going to the turbine). Also, the air leaving the evaporator needs to be induced or stirred so that it goes evenly to the reheat condenser that regulates the drying temperature.

It is a side view of a pressure vessel and an evaporator (method without an induction plate). It is sectional drawing of the part of the evaporator of a pressure vessel. (Common to the lateral views of FIGS. 1 and 3) It is a side view of a pressure vessel and an evaporator part of a system with a guidance board in the front and rear parts of an evaporator. FIG. 4 is a layout diagram of equipment piping of a refrigerator that employs the pressure vessel method of FIG. 3.

Explanation of symbols

1 Air compressor 2 Compressed air piping 3 Compressed air pressure inlet 4 Pressure vessel 5 Evaporator 6 Side plate for fixing refrigerant piping 7 Refrigerant piping 8 Air outlet 9 Drain drainage pipe 10 Motor
11 pressure vessel front 12 induction plate 13 pressure vessel evaporator 14 pressure vessel rear 15 dehumidifier 16 expansion turbine 17 refrigerant compressor 18 condenser 19 expansion valve 20 refrigerator compartment

Claims (4)

  A refrigerator having a pressure vessel for storing an evaporator of the refrigerator and an air compressor for press-fitting air to be cooled into the pressure vessel. The refrigerator according to claim 1, wherein a leeward portion of the evaporator can be opened and closed with respect to a pressure vessel that houses the evaporator.   The refrigerator according to claim 1 or 2, wherein a size and a shape of a portion of the pressure vessel accommodating the evaporator through which the air to be cooled passes through the evaporator match a size of the evaporator.   There are a plurality of pressure inlets and outlets of the pressure vessel containing the evaporator, or in the pressure vessel, an induction plate is provided in front of and behind the evaporator so that air uniformly contacts the fins of the evaporator. The refrigerator according to claim 1 and claim 2.

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